Remote control command system

ABSTRACT

A remote control system protected against enemy take-over and particularlyuited for the undersea control of acoustic decays and torpedoes. System includes dual electronics systems. Command signal includes plurality of frequencies which disable one of dual systems and energizes the other system.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a remote control command system andmore particularly to a remote control system for various militarydevices which must be protected from enemy take-over.

2. Description of the Prior Art

Systems, using both electromagnetic and acoustic linking signals, havealready been developed for the remote control of a wide variety ofobjects ranging from home TV sets and model airplanes to torpedoes,missiles and space equipment.

However, these previously developed systems have not been entirelysatisfactory for military use because of the danger of enemy take-overeither in the form of jamming signals or (a more remote but very seriouspossibility) by signals that actually control the military device forthe enemy's purpose.

SUMMARY OF THE INVENTION

The general purpose of this invention is to provide a remote controlsystem which embraces all of the advantages of prior remote controlsystems and that contains features which protect against enemytake-over. To attain this protection, the present invention contemplatesthe use of dual receiver systems which are responsive to differentfrequency ranges and command signals which include a plurality offrequencies. One of the signal frequencies disables one of the receiversystems and enables the other receiver system. The remainder of thesignal frequencies energize the enabled receiver system to perform thecommanded function.

It is, therefore, an object of the present invention to provide animproved remote control system that is protected against enemytake-over.

Another object is to provide an improved remote control system that isprotected against enemy take-over and includes dual receiver systems.

A still further object is to provide an improved remote control systemthat is protected against enemy take-over and includes dual receiversystems and a multi-frequency command signal which disables one of thedual receiver systems and energizes the other.

DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the invention will hereinafter becomemore fully apparent from the following description of the annexeddrawings wherein:

FIG. 1 illustrates a first embodiment of the invention as used in thecontrol of a torpedo and

FIG. 2 shows a second embodiment of the invention as used in the controlof an acoustic decoy.

DESCRIPTION OF THE INVENTION

The invention will be described, as initially contemplated, for use inunderwater military devices, such as torpedoes and acoustic decays,where the command signal is acoustic in nature. However, it will beapparent that the invention is not limited to such underwaterapplications and can be used in many other environments, such as in theremote control of missiles, satellites, space equipment, etc. by meansof an electromagnetic command link.

Referring now to the drawings, wherein like reference charactersdesignate like or corresponding parts, there is shown in FIG. 1 anembodiment of the invention which is adapted to control a torpedo.

Most modern torpedoes have three stratum settings, usually designated asabove limit (AL), below limit (BL) and no limit (NL). When set in AL,the torpedo is armed from the surface to a depth limit, usually 100feet, and disarmed below this depth limit. When set in BL, the torpedois disarmed from the surface to the depth limit and armed below thisdepth limit. When set in NL the torpedo is armed at all depths.

Several incidents wherein the torpedo has missed the target and thenacquired and hit the launching ship have emphasized the need of a remotecontrol system for torpedoes and have caused the avoidance, unlessrequired by military necessity, of launching torpedoes which are armedin the same stratum as occupied by the launching ship. This practiceobviously places a limitation on the efficient A use of torpedoes. Theembodiment of the invention illustrated in FIG. 1 removes the need forstratum separation between the torpedo and the launching ship byproviding the means whereby the path of the torpedo can be controlledfrom the launching ship.

Referring now to FIG. 1, the broad band acoustic transducer 10 ispositioned on the torpedo in such a manner as to be energized byacoustic command signals propagated through the sea from the launchingship and produces electric signals which are amplified by the amplifier12. Both the acoustic command signals and the resultant electric signalscontain several different frequency components for purposes which willbe discussed later. These frequency components are separated and passedinto the dual receiver systems 20 and 30 by band pass filters 22a, b andc, 32a, b and c, all of which are connected to the output of amplifier12. The pass bands of filters 22a, b and c are all different from eachother and are lower in frequency than the pass bands of filters 32a, band c, Which are also different from each other. An additionalrequirement is that not any of the filter pass bands be harmonicallyrelated to each other.

Each of the filters 22a, b and c, 32a, b and c are respectivelyconnected to Schmitt trigger circuits 24a, b and c, 34a, b and c. Thetriggers 24c and 34c are in turn connected to inverter circuits 26 and36 which function either to convert the trigger "high" state signals tolow potential signals or to convert the trigger "low" state signals tohigh potential signals. As illustrated the AND gates 28a and 28b arerespectively connected to receive the output signals of inverter 26,trigger 34c and triggers 24a or 24b. Similarly the AND gates 38a and 38bare respectively connected to receive the output signals of inverter 36,trigger 24c and triggers 34a or 34b. The AND gates 28a and b, 38a and beach function to produce a signal only when a high signal is received onall three inputs.

OR gate 40 is connected to receive any output signals from the AND gates28a and 38a and, in turn, to energize the right turn control 42 whichcauses the torpedo to make a right turn. Similarly the OR gate 44 isconnected to receive any output signals from the AND gates 28b and 38band, in turn, to energize the left turn control 46 which causes thetorpedo to make a left turn.

The operation of the embodiment of the invention illustrated in FIG. 1will now be described in the environment of a torpedo although it willbe apparent that this embodiment could also be located on and controlother types of vehicles and that electromagnetic command signals couldbe used, where appropriate, rather than the described acoustic commandsignal.

For descriptive purposes, let it be assumed that it is desired tocommand a torpedo carrying the embodiment of FIG. 1 to make a rightturn. To accomplish this result the command vessel propagates anacoustic command signal through the sea. This acoustic command signal isreceived and changed into an electric signal by the transducer 10. Itwill be realized, of course, that the acoustic and electric signalscontain the same frequency components. These frequency components arechosen so that one component will pass through filter 22a and energizetrigger 24a to produce a first high state signal input to AND gate 28a.The command signal also includes a frequency component which is in thepass band of filter 32c and which energizes trigger 34c to produce asecond high state input signal to AND gate 28a. Inverter 36 converts thehigh state output of trigger 34c to a low state signal which disablesthe AND gates 38a and 38b. The command signal will not contain afrequency component in the pass band of filter 22c since trigger 24cmust be maintained in the low state. This low state signal is convertedby inverter 26 to a high state signal which constitutes the third highstate input signal to AND gate 28a. The three high state input signalscause AND gate 28a to produce a signal which is applied through OR gate40 to energize the right turn control 42 and thereby cause the torpedoto make a right turn.

Various reasons, such as an enemy jamming signal which energizes trigger24c, may cause the torpedo not to respond to the command signal. As soonas this is apparent, the command signal can be changed to containfrequency components in the pass band of filters 22c and 32a and therebycause AND gate 38a to energize the right turn control 42.

It is, of course, evident that left turns, if desired, can be commandedeither by a command signal containing either frequency components in thepass bands of filters 22b and 32c, but not in 22c, or in the pass bandsof filters 32b and 22c, but not in 32c.

Enemy countermeasures can be successful in disabling the embodiment ofFIG. 1 only if jamming is present in A both of the regions of thespectrum in which the dual receivers 20 and 30 operate. Since theseregions can be quite widely separated, the chance of successful jammingis minimized.

Because of the tremendous importance of submarine warfare, much effortis currently being directed toward developing sonar countermeasures forthe purpose of protecting our submarines from sonar detection and attackby acoustic torpedoes, i.e. torpedoes which are guided to their targetby sonar equipment carried in the torpedo. One of the most promising ofthese sonar countermeasures is the so-called acoustic decoy which islaunched from the submarine and functions to propagate acoustic signalswhich cause search sonar or acoustic torpedoes to lock on (track) theacoustic decoy.

Referring now to FIG. 2, the broad band acoustic transducer 10 ispositioned on the decoy in such a manner as to be energized by acousticsignals being propagated through the sea. These signals may be eitherthe command signals from the command submarine or enemy sonar searchsignals or the guidance sonar signals of an enemy acoustic torpedo.Transducer 10 converts the received acoustic signals into electricalsignal which are amplified by amplifier 12 and then applied to the dualreceivers 50 and 60 and to the decoy electronics 80 which customarily,for the purpose of deceiving the enemy, propagate an "echo" of thereceived signal by means of the transducer 82.

The dual receivers 50 and 60 operate at different regions in thefrequency spectrum, i.e. the pass bands of filters 52a . . . n are muchlower than the pass bands of filters 62a . . . n. All of the pass bandsare for different frequencies which are not harmonically related to eachother. The filters 52a . . . n and 62a . . . n are individuallyconnected to the output of amplifier 12 and are in turn connected totriggers 54a . . . n and 64a . . . n which are similar in function tothe triggers 24a, b and c and 34a, b and c of the previously describedembodiment of FIG. 1.

Triggers 54a . . . m and 64a . . . m are respectively connected to logiccircuits 56 and 66 which are not, per se, a part of this invention. Thelogic circuits 56 and 66 function to provide a signal to a particularone of each set of AND gates 58a . . . r and 68a . . . r according towhich combination of triggers 54a . . . m and 64a . . . m are energizedto be in the high state. Many logic circuits, often in the form of adiode matrix, are known in the prior art and are suitable for use as thelogic circuits 56 and 66. Triggers 54n and 64n are connected toinverters 26 and 36 which function, in a manner similar to thatdescribed in the embodiment of FIG. 1, to enable and disable the dualreceivers 50 and 60.

The signal from the particular one of the AND gates 58a . . . r, 68a . .. r is applied through OR gates 70a . . . r to energize one of thestepping switches 72a . . . i to either increase or decrease acontrolled function of the decoy. For purposes of example the switches72a . . . i may control in both directions the steering and aspect ofthe decoy and the doppler frequency shift and gain settings in the echocircuits 80 which produce the signal propagated by transducer 82.

Energization of any of the switches 72a . . . i also energizes theblanking circuit 74 which functions to disable the echo circuits 80 andprevent the propagation, by transducer 82, of any "echoes" of thesubmarine command signal.

It is by now probably apparent that the operation of the embodiment ofFIG. 2 is as follows. When the "pings" of search sonar or acoustictorpedo guidance sonar are received by transducer 10, "echoes" of thesepings are produced and propagated by the circuit 80 and transducer 82for the purpose of deceiving the enemy into believing his sonar signalshave been reflected from a submarine. These "pings" will not energizethe receivers 50 or 60 since the necessary presence and absence offrequency components will, almost of a certainty, not be present in the"ping".

The command signal from the submarine, by which some operational changein the decoy will be ordered, will contain a frequency component in thepass band of one, but not both, of the filters 52n or 62n. For purposesof illustration a frequency component in the pass band of filter 62n isassumed. The command signal will also include one or more frequencycomponents in the pass bands of the filters in the other receiver,assumedly receiver 50, that is one or more frequency components in thepass bands of the filters 52a . . . m. These frequency components willenergize logic circuit 56 (by means of triggers 54a . . . m) to produceand apply a signal to a particular AND gate 58a. This particular gate,and the others of the gates 58a . . . r, will also have enabling signalsapplied by inverter 26 and trigger 64n. All of the gates 68a . . . rwill be disabled by inverter 36. The signal produced by the particularAND gate 58a . . . r energizes, through one of the OR gates 70a . . . r,one of the stepping switches 72a . . . i to thereby cause the desiredchange in the operation of the decoy. Energization of the steppingswitch also causes blanking circuit 74 to disable echo circuits 80 andprevent the propagation of an echo signal (by transducer 82) as a resultof the reception of the command signal.

Various reasons, such as an enemy jamming signal which energizes trigger54n, may cause the decoy not to respond to the command signal. As soonas this is apparent, the command signal can be changed to containfrequency components in the pass bands of the filters 52n and 62a . . .m, but not 62n. Enemy countermeasures can be successful in disabling theembodiment of FIG. 2 only if jamming is present in both of the regionsof the spectrum in which the dual receivers 50 and 60 operate. Sincethese regions can be quite widely separated, the chance of successfuljamming by the enemy is minimized. However, in the event that the enemyis successful in jamming the pass bands of both filters 52n and 62n, theecho circuits 80 would continue to operate since the blanking circuit 74would not be energized and consequently the decoy will continue tofunction and propagate "echo" signals as a result of the jamming signalsreceived by transducer 10. These "echo" signals may deceive the enemyinto believing that the jamming signals were reflected from a submarine.

There has been disclosed embodiments of an improved remote controlsystem which are particularly adaped to use in torpedoes and acousticdecays and that are protected against enemy take-over and include dualreceiver systems and utilize a multi-frequency command signal whichdisables one of the dual receiver systems and energizes the other.Obviously many other embodiments of the present invention, adapted toother environments, are possible in the light of the above teachings. Itis therefore to be understood, that within the scope of the appendedclaims, the invention may be practiced otherwise than as specificallydescribed.

What is claimed and desired to be secured by Letters Patent of theUnited States is:
 1. A remote control system comprising:First and secondreceiving means, said first receiving means being connected to receiveand be responsive to command signals in a first frequency region andsaid second receiving means being connected to receive and be responsiveto command signals in a second frequency region which is separated fromsaid first frequency region; Disabling means in each of said first andsecond receiving means, said disabling means being connected to receiveand be responsive to command signals of particular frequencies in saidfirst and second regions, each of said disabling means, when responsiveto a command signal, functioning to disable one of said receiving meansand enable the other of said receiving means and Control means connectedto said first and second receiving means and energized by commandsignals in the frequency region to which said enabled one of saidreceiving means is responsive.
 2. A remote control system as set forthin claim 1 wherein said first and second receiving means each includes aplurality of filters connected to receive said command signals, each ofsaid filters having a pass band that is different from and notharmonically related to the pass bands of the others of said pluralityof filters.
 3. A remote control system as set forth in claim 2 whereineach of said receiving means further includes a plurality of triggermeans individually connected to said plurality of filters.
 4. A remotecontrol system as set forth in claim 3 wherein each of said disablingmeans includes an inverter connected to the trigger means which is inturn connected to the filter having a pass band that includes one ofsaid particular frequencies.
 5. A remote control system as set forth inclaim 4 wherein said first and second receiving means further eachinclude a plurality of AND gates, the output of said AND gates beingconnected to said control means and wherein the input of each AND gateincludes a first signal from the output of one of said inverters, asecond signal from the input of the other of said inverters and a thirdsignal resultant from the energization of at least one of said triggermeans.
 6. In combination with a torpedo, a remote control systemcomprising:Transducer means for receiving multi-frequency acousticcommand signals and for producing similar multi-frequency electricalcommand signals; First and second receiving means, said first receivingmeans being connected to receive and be responsive to frequencycomponents of said multi-frequency electrical command signals which arein a first frequency region and said second receiving means connected toreceive and be responsive to frequency components of saidmulti-frequency electrical command signals which are in a secondfrequency region which is separated from said first frequency region;Disabling means in each of said first and second receiving means, saiddisabling means being connected to receive and be responsive toparticular frequency components of said electrical command signals whichare in said first and second regions, each of said disabling means, whenresponsive to a command signal, functioning to disable one of saidreceiving means and enable the other of said receiving means and Controlmeans for varying the operative characteristics of said torpedo andconnected to said first and second receiving means and energized byfrequency components of said electrical command signals which are in thefrequency region to which said enabled one of said receiving means isresponsive.
 7. The combination as set forth in claim 6 wherein saidfirst and second receiving means each includes a plurality of filtersconnected to receive said multi-frequency electrical command signals,each of said filters having a pass band that is different from and notharmonically related to the pass bands of the others of said pluralityof filters.
 8. The combination as set forth in claim 7 wherein each ofsaid receiving means further includes a plurality of trigger meansindividually connected to said plurality of filters.
 9. The combinationas set forth in claim 8 wherein each of said disabling means includes aninverter connected to the trigger means which is in turn connected tothe filter having a pass band that includes one of said particularfrequency components.
 10. The combination as set forth in claim 9wherein said first and second receiving means further each include aplurality of AND gates, the output of said AND gates being connected tosaid control means and wherein the input of each AND gate includes afirst signal from the output of one of said inverters, a second signalfrom the input of the other of said inverters and a third signalresultant from the energization of at least one of said trigger means.11. In combination with an acoustic decoy, a remote control systemcomprising:Transducer means for receiving multi-frequency acousticcommand signals and for producing similar multi-frequency electricalcommand signals; Echo signal means connected to said transducer meansfor producing acoustic signals in response to said electrical commandsignals; First and second receiving means, said first receiving meansbeing connected to receive and be responsive to frequency components ofsaid multi-frequency electrical command signals which are in a firstfrequency region and said second receiving means connected to receiveand be responsive to frequency components of said multi-frequencyelectrical command signals which are in a second frequency region whichis separated from said first frequency region; Disabling means in eachof said first and second receiving means, said disabling means beingconnected to receive and be respectively responsive to particularfrequency components of said electrical command signals which are insaid first and second regions to disable one of said receiving means andenable the other of said receiving means; Control means for varying theoperative characteristics of said echo signal means and of said decoy,said control means being connected to said first and second receivingmeans and energized by frequency components of said electrical commandsignals which are in the frequency region to which said enabled one ofsaid receiving means is responsive and Blanking means connected to saidcontrol means and to said echo signal means to prevent said echo signalmeans from producing an acoustic signal When said control means areenergized.
 12. The combination as set forth in claim 11 wherein saidfirst and second receiving means each includes a plurality of filtersconnected to received said multi-frequency electrical command signals,each of said filters having a pass band that is different from and notharmonically related to the pass bands of the others of said pluralityof filters.
 13. The combination as set forth in claim 12 wherein each ofsaid receiving means further includes a plurality of trigger meansindividually connected to said plurality of filters.
 14. The combinationas set forth in claim 13 wherein each of said disabling means includesan inverter connected to the trigger means which is in turn connected tothe filter having a pass band that includes one of said particularfrequency components.
 15. The combination as set forth in claim 14wherein said first and second receiving means further each include alogic circuit which is connected to all of the trigger means in thatreceiving means except the trigger means which is connected to saidinverter.
 16. The combination as set forth in claim 15 wherein saidfirst and second receiving means further each include a plurality of ANDgates, the output of said AND gates being connected to said controlmeans and wherein the input of each AND gate includes a first signalfrom the output of one of said inverters, a second signal from the inputof the other of said inverters and a third signal from a connection tothe output of said logic circuit.